of detroit



Nov. 11, 1924. 1,515,308

H. C. MAUL ELECTRIC HEATING DEVICE Filed March 19 19 3 Patented Nov. 11,1924.

v UNITED STATES PATENT OF F ICE.

H ENRY C. MAUL, OF DETROIT, MICHIGAN, ASSIGNOR TO THE MICHIGAN STOVECOM- PAN'Y, OF DETROIT, MICHIGAN, A CORPORATION OF MICHIGAN.

} ELECTRIC 'HEATING nEvIcE.

Application filled March 19, 1923. Serial No. 625,977.

To all whom it may concern:

Be it known that I, HENRY C. MAUL, a citizen of the United States ofAmerica, residing at Detroit, in the county of Wayne and State ofMichigan, have invented certain new and useful Improvements in ElectrioHeating Devices, of which the followlng is a specification, referencebeing had therein to the accompanying drawings.

This invention relates to an electric heating device and has specialreference to a unitary structure that may be advantageouslyembodied inthe cooking top of an electric range, stove or other structure and uponwhich cooking utensils may be expeditiously heated with a minimum lossof heat because of any radiation downwardly into the range or stove.

My invention aims to provide a novel heating device embodying acomparatively flat volute two-part armored heating element which issomewhat in the form of a scroll or nested coils supported for intimate,metal to metal, contact with a cooking utensil placed on the heatingelement, so as to insureagood heating conductor. The manner ofsupporting the convolutions of the heating element is such that certainconvolutions or portions of, the heating element may be depressedbecause of the weight of a cooking utensil on the heating element,

thus obtaining a positive contact of the heating element with the bottomoi the cookin utensil.

g y invention further aims to provide supportingme-ans for a coiledheating element with the supporting means compensating for expansion andcontracting; affording a ready means of supporting the heating devicerelative to the cooking top of an electric range; insuring a thoroughinsulation of the heating element relative to other parts of the cookingrange or stove, and providing a convenient means of making electrical.

- and 2 denote volute spiral heating coils or elements,- 3 an uppersupporting member; 4 an insulator and 5 a lower supporting member.

Each of the armored heating elements 1 and are in the form of acomparatively flat coil tubular throughout with the inner and outerconvolutions of each coil terminating in ends 6 disposed substantiallyata right angle to the plane of said coil, which have the convolutionsthereof somewhat widly separated so that one coil may be placed Withinthe other thus bringing the ends 6 of the inner coil convolutions inproximity to each other and with said coils of a predetermined lengththe ends of the outer convolutions can be brought into a common platetransverse of the heating device with the ends of the inner convolutionsat opposite sides of such plane. Such an arrangement of the coil endswill facilitate making electrical connections with said coils as willhereinafter appear. Each coil com.- prises a. tubular armor containinginsulation material and a resistance coil, the insulation material beinggenerally designated 7 and each resistance coil having terminals 8protruding from the ends 6 of said coils. so that nuts 9 or otherdevices can be mounted on said terminals for holding a connector 10 andleadingin wires. The connector 10 is in the form of a bar havingapertured ends to receive t-he terminals 8 of the inner convolutions ofthe coils. The interior construction of each coil may be considered of aconventional form and I use such armored coils because the same can beeasily shaped to form a comparatively flat heating element on the uppersupporting member 3, because said coils can be supported other than bydirect attachment to the upper supporting member 3 and because of thelarge protected or armored heating surface of such coils when arrangedas a single heating element. In addition to this there is the inherenttendency of some of the convolutions to extend above the plane of theinner and outer fastened convolutions, consequently the intermediateconvolutions will be susceptible to depression by a cooking utensil onthe heating element and the weight of such utensil will insure anintimate, metal to metal, contact and permit of the utensil absorbingpractically all the heat. With the ends 6 of the element coils extendingthrough the insulator 4 and below the lower supporting stove.

60 pact heating device.

what in the form of adisk which has a flat central portion 11,circumferential corrugations 12 providing ridges 13, and a rim '14 bywhich the heating device may be sup ported from the cooking top of arange or The rim 14 also cooperates with the outermost ridge 13 informing an annular trough 15 preventing, to a large extent, spilled oroverboiled. liquids or substances from contacting with the insulator 4.The

upper supporting member 3 is preferably made of metal and thecircumferential corrugations will compensate for expansion andcontraction and prevent buckling of the central portion of said member.The ridges 13 90 of the corrugations will constitutesupports for theconvolutions of the heating coils and with such line or point contactbetween the coils and the upper supporting member there will be aminimum loss of heat through the upper supporting member. Then again,

the supporting member may be made of aluminum or some metal having afinish which will reflect heat from the heating coils.

circular brick or slab provided with openings for the ends 6 of theheating coils, also a central opening for a nut equipped tie rod or bolt16 by which the insulator is firmly held and sandwiched between theupper and lower supporting members. This insulator being made of aporousmaterial, liable to crumble, it protected by the supporting members 3and 5, particularly-the upper supporting member 3 which prevents soapsor hot liquid substances from contacting with the insulator, carbonizingon it, rendering 1t unsanitary, and practically useless for in sulationpurposes.

or structure which supports it and bv being sandwiched between the upperand lower supporting members it cooperates with these members inproviding a substantial com- The lower supporting member 5 is in theform of a metallic disk on the lower face of the insulator 4: and saidsupporting member has an annular upstanding flange 17 protectlfi ing thelower edges of the insulator 4. It

also prevents-the insulator from being inured by nuts 18 or otherholding devices mounted on the ends 6 of the heating coils,

said-nuts being tightened against the lower 60 supporting member tofirmly hold the heat mg coils 1 and 2 on the ridges 13 of the uppersupporting member 3.

In addition to the central tie rod or bolt 16 there may be alpluralityof nut equipped .5 tie rods or bolts 19- tying the upper and Theinsulator avoids- 4 radiation of heat downward into the range lowersupporting-members together adjacent the marginal edges thereof.

I attach considerable importance to the fact that practically the entirearmored su'rface of the heating element is exposed above the heatreflecting upper. supporting memher, in contradistinction' to beingcountershown it to be far superior to any heating elements, for cookingpurposes, which I have ever tested.

Gne embodiment of my invention has been illustrated, but it is tobeunderstood that the structural elements are susceptible to suchvariations and modifications as fall within the scope of the appendedclaims,

What I claim is V 1. In a heating devicefa one piece supportingmembercorrugated to provide circumferential ridges, and a heatingelement resting on the ridges of said supporting member and having endsextending downwardly through said supportingmember. The insulator 4 ispreferably made of a so very porous material in the form of a thick 3. Aheating deviceas called for 'in claim 1, wherein said heating element isin the form of volute armored coils, one coiled within theother, and\the convolutions of both coils substantially in a common plane andadapted for supporting a utensil.

gt. In a cooking device,a supporting member, and a comparatively flatvolute armored heating element having convolutions above said supportingmember adapted by the weight of a cooking utensil directly on theconvolutions of said heating element to establish a positive contactwith the bottom iof said cooking utensil for heating purposes.

5. A heating device comprising an insulator, upper and lower supportingmembers on said insulator, and'a heating element in a plane above theupper supporting member and having electrical connections through saidinsulator.

6. A heating device as called for in claim '5, wherein said heatingelement is in the I form of a coil having ends extending through saidsupporting members and said insulator.

7. A heating. device as called for in claim 5, wherein the uppersupporting member is circumfer'ent-ially corrugated to compensate forexpansion and contraction because of the heat of said "heating element,

v 8. A heating device as called for in claim 5, wherein the uppersupporting member has an overhanging annular edge 'afiording a troughand means to facilitate supporting; said heating device relative to thecooking top of an electric range.

9. A heating deviceas called for in claim 5, wherein the uppersupporting member has ridges supporting said heating element withportions of said heating element adapted to be brought into contact withsaid ridges by the weight of a cooking utensil on said heating element.

'10. A heating device as called for in claim 5, and means on saidheating element main-l taining said supporting members on saidinsula'tor.

11. A heating device as called for in claim I 5, and means extendingthrough said supporting members and said insulator maintaining saidsupporting members and said insulator assembled, and means on saidheating element against the lower supporting member maintaining saidheating element above the upper supporting member.

12. A heating device comprising upper and lower supporting members, aporous insulator sandwichedbetween said supporting connections for theouter convolutions of said heating coils, said -connector and saidelectrical connections being below said lower supportin" member.

14. In a cooking device, a supporting member, and a comparatively fiatvolute two-part armored heating element above said supporting memberadapted by the weight of a cooking utensil on said heating element toestablish a positive contact with the bottom of said cooking utensil forheating purposes, the parts of said heating element being coiled onerelative to the other and both parts forming a circular cooking top forsaid device.

In testimony whereof I afiix my signature in presence of two witnesses.

' HENRY C. MAUL. Witnesses: I

NINA G. DnouILLARn, IDA MENDELL.

